This invention relates to a foldable leg assembly specially adapted for use with workbenches and other heavy duty applications where strength, stability, ease of access and simplicity of construction are of primary importance. The invention is particularly adapted for use in workbenches the invention is particularly adapted for use in workbenches and the like wherein a dual height working surface is desired and, accordingly utilizes pivotally mounted legs movable from a folded inoperative position corresponding to the lower of the two positions to an unfolded operating position corresponding to the higher of the two positions.
One form of workbench for which the present invention is particularly suited is described in U.S. Pat. No. 3,615,087 issued Oct. 26, 1971 to R. P. Hickman. This patent describes a workbench including a support bearing a pair of top members lying in a plane and defining a working surface with at least one of the top members being movable towards and away from the other upon actuation of a pair of spaced independently operable clamping devices to vary the gap between the top members and permit the clamping of a wide variety of work pieces relative to the work surface. The support structure includes a rectangular base and a frame assembly extending between the base and the top members. The frame assembly includes a pair of frame members pivotally connected in such fashion as to permit movement between an erected working position wherein the top members are spaced above the base and a collapsed position in which the top members are in close juxaposition to the base.
In order to provide a dual height working surface for the above noted structure, there has hitherto been provided a foldable leg structure for securement to the base member. Such leg structure included a leg pivotally connected at each of the four corners of the rectangular base in such manner that, when folded, the legs move into general alignment with the opposed ends of the base. In order to support the legs in the unfolded or erected position, foldable braces or struts were employed. However, such foldable braces, in addition to making the structure somewhat more complicated, made the structure more difficult to manipulate; furthermore, the braces, in their erected positions, were apt to interfere with the user's feet and thus affect the user's forward access to the workbench.
There is also the problem of stability to be considered. In the higher of the two positions of the workbench there is the requirement that the support legs be oriented such that increased resistance to tipping of the workbench is provided. Good stability is an extremely important requirement when it is considered that, in workbenches of the type discussed above, the user often sits upon a portion of the working surface of the workbench, depending on the nature of the work being done, and thus is apt to be injured if the workbench topples over.
With further reference to typical prior art structures, it is noted that various types of folding leg structures have been provided on lightweight card tables and portable picnic tables. However, in general, it may be said that these structures are not suitable for heavy duty use in workbenches or the like since the overall design of the pivot bracket in most of these structures is unduly complex and thus overly costly to produce particularly in applications where high strength is required. In addition, the design of the legs, per se, is usually inadequate for applications where relatively large forces and bending moments may be involved.